The elongated building covers the whole breadth of the narrow plot of ground situated between a busy main road and a protected area of farmland. It combines two contrasting motifs: long, solid walls and a light, apparently floating glass roof. All the external walls are clad with red porphyry from Patagonia (Argentina). The building is supported by four 127 metre-long parallel load-bearing walls placed at intervals of about seven metres. The two end façades are made of glass and look out over the park. On the road side, the museum is completed by a windowless wall that protects the building and on the inside. A large glass roof lets daylight into the whole building. Unlike conventional top lighting, this roof allows the zenithal daylight to filter into the building’s interior in its natural state instead of homogenising it and making it diffuse and milky. There are also three systems with artificial light sources that illuminate the rooms when there is insufficient light from outside.